News

Dye has agglomeration phenomenon

Release time:

2020-04-13 10:36

Dyeing aluminum oxidation treatment in the dyeing time is longer prone to dye flocculation phenomenon, the reasons and countermeasures are as follows:

1. Adsorption mechanism of dyes in aluminum oxide film.

The adsorption mechanism of the dye on the anodic oxide film is that the dye molecules penetrate from the entrance of the aluminum anodic oxide film to the move, and the dye molecules are fixed and attached to the inner wall of the aluminum anodic oxide film.

The dye molecules in the dyeing court are not single molecules, but are suspended in the state of several molecular groups. Different structures have different concentration levels. The molecules of this dye group are combined and fixed in the inner wall of the micropores. It is difficult for all the molecules of the dye group to completely adhere to the inner wall of the micropores, the remaining part of the dye molecules that cannot be attached exists in the micropores of the oxide film.

 

2. The micropore direction of the anodic oxide film of the dye molecular phase moves slowly, and it can be expected that the longer the dyeing time, the more residual dye molecules.In the subsequent water washing process, the dye molecules in the remaining part will slowly flow out from the micropores as the washing water is placed for a longer time.

In the subsequent sealing process, the residual dye molecules adsorbed by nickel in the high-temperature sealing solution are extruded from the micropores of the oxide film, and the sealing solution contains more fluorine 'phosphorus plasma that is easy to combine with you to extrude more residual dye molecules, while the fluorine' phosphorus plasma is adsorbed on the micropore wall.

The residual dye molecules thus extruded adhere to the surface of the anodic oxide film and exhibit an agglomeration phenomenon.
It can be seen that the longer the dyeing time, the more residual dye, which is the cause of dye flocculation.
Other reasons are insufficient dissolution of the dye itself, and the adsorption of aluminum hydroxide and nickel hydroxide occurs when the surface of the aluminum anodic oxide film is sealed. Ionized substances in the sealing solution are precipitated due to drying, and these will be agglomerated.

 

3. A method to prevent agglomeration of dyed aluminum anodized dyes.

1) Key points for attention in the construction and supplement of dyeing tank.

Dyes are very insoluble substances, and there are also dyes with a solubility of about 3 grams per liter at 20 degrees. Consider the attachment of insoluble components.SlotAnd supplement, can be more than 90 degrees of hot water fully dissolved, if not pre-dissolved, then the insoluble part suspended in the dyeing solution, not only attached to the surface of the aluminum anodic oxide film, but also in the mixed dye will affect the color change.

2) The dye concentration of the dyeing tank.

For the benefit of black, a dye concentration of eight to ten grams per liter is usually recommended. When it is used continuously, it sometimes exceeds ten grams, and the concentration of dye per liter increases, and the probability of agglomeration of dyeing molecules will also increase, which requires attention.

3) pH management of dyeing tide.

The adjustment of pH is the most important in the management of the dyeing bath. It is most important to control the most suitable pH range of each dye, and it is necessary to adjust with dilute acetic acid and ammonia water in cases outside the pH management value.

Regarding the prevention of dye flocculation, the dyeing management should be performed as described above while shortening the dyeing time, and the management only for the purpose of keeping the dyeing in a good working state is the most important.

 

Aluminum anode